ROME: The United Nations' food agency said yesterday its was mobilizing its animal health experts and sending some to Mexico to check if the new strain of flu virus widely described as swine flu is really directly linked to pigs.

"At present, transmission seems to be occurring solely from humans to humans," said the Food and Agriculture Organization (FAO).

"So far evidence that the new strain of influenza A virus has entered the human population directly from pigs has not been established," the Rome-based UN body said in a statement.